Which of the following does not belong to a projected aid ?
2012
Which of the following does not belong to a projected aid ?
Answer: B. Blackboard — Concept — Teaching aids are grouped by how their content reaches the learner's eye. A projected aid stores its material on a transparency, a slide or a page…
- A.
Overhead projector
- B.
Blackboard
- C.
Epidiascope
- D.
Slide projector
Show answer & explanation
Correct answer: B
Concept — Teaching aids are grouped by how their content reaches the learner's eye. A projected aid stores its material on a transparency, a slide or a page and needs a light source together with an optical (lens) system to cast an enlarged image of that material onto a separate screen. A non-projected aid carries its content on its own surface and is read straight off that surface, with no lamp, lens, screen or darkened room.
Application — Apply that single test to each aid named here: is a lamp-and-lens system needed to form the image on a separate screen?
Aid | How the content is displayed | Class |
|---|---|---|
Overhead projector | A lamp under the glass platen lights a transparency; the head-mounted lens and mirror throw the enlarged image on a screen | Projected |
Epidiascope | A lamp lights an opaque page or a slide inside the housing; the objective lens throws the enlarged image on a screen | Projected |
Slide projector | A lamp shines through a mounted film slide; the objective lens throws the enlarged image on a screen | Projected |
Blackboard | Chalk marks sit on the coated panel itself and are read directly off that panel in ordinary room light | Non-projected |
Cross-check — Take the electricity and the screen out of the room. The overhead projector, the epidiascope and the slide projector all fall silent, because each of them forms its image only through a lamp and a lens. The chalk-written board is untouched, since its content already sits on the board's own surface — which is why a blackboard is the standard textbook example of a non-projected, display-board aid.
Result — Hence the aid that does not belong to the projected group is the Blackboard.